As for this type of connector device, there have been proposed a variety of devices conventionally (see JP 2000-182702 A (PTL 1) and US 2010/0003841 A1 (PTL 2)). A first conventional example of such connector devices is illustrated in FIG. 1. In FIG. 1, a connector device 50 according to the first conventional example is installed in a cylinder head 70 of an engine to pick up an output of a built-in fuel pressure sensor element (not illustrated). The connector device 50 includes a wire harness side connector 51 and a sensor side connector 60.
The wire harness side connector 51 includes a housing part 52. A first terminal 53 is disposed in an interior portion on one end side of the housing part 52. An external terminal 54 is disposed in an interior portion on the other end side of the housing part 52. The first terminal 53 is connected to the external terminal 54 through wires W accommodated in the housing part 52. The housing part 52 includes a connector fitting part 52a housing the external terminal 54. An external connector (not illustrated) is fitted to the connector fitting part 52a. 
The sensor side connector 60 includes a sensor body part 61 in which a sensor element (not illustrated) is disposed, and a housing part 63 which is fixed to the sensor body part 61 and in which a second terminal 62 is disposed. A threaded part 61a is formed on the outer circumference of the sensor body part 61. By screwing the sensor body part 61 into a threaded hole 70a of the cylinder head 70, the sensor side connector 60 is installed in the cylinder head 70.
With the above mentioned constitution, the sensor side connector 60 is installed in the cylinder head 70 and thereafter, a head cover 71 is mounted on the cylinder head 70. Then, the wire harness side connector 51 is inserted into a hole 71a of the head cover 71 and fitted to the sensor side connector 60.
As a second conventional example, additionally, a connector device illustrated in FIG. 2 is also proposed. In FIG. 2, a connector device 80 according to the second conventional example has a circular cross section and is connected to a glow plug (not illustrated), as a plug-in connector for a diesel engine. The connector device 80 includes a resinous base body 84 having three coaxially arranged contact shoes 81 to 83, a housing part cap 85 having locking means (not illustrated) for locking the connector device 80 to another glow-plug connector, and a plurality of contact lugs 86 connected to an engine control unit (not illustrated) through wires (not illustrated).